<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>

        .a {
            opacity: 0.5;
            filter: alpha(opacity=50);


            /* 谷歌 */
            -webkit-transition: 1s;
            /* FF */
            -moz-transition: 1s;
            /* IE */
            -ms-transition: 1s;
            /* O */
            -o-transition: 1s;
            transition: 1s;


            box-shadow: ;

            transform: ;

            background-size: ;


            


            background:-webkit-linear-gradient() ;

            display: -webkit-flex;
        }
    </style>
</head>
<body>

    <!-- 

        Trident  IE 
        Gecko    FF
        Presto   O
        Webkit   chrome / safari .... 
        Blink   欧朋和谷歌共同开发  

     -->


    opacity:0 ;
    filter:alpha()


    图片的间距



    
</body>
</html>